Transcranial Magnetic Stimulation in the Diagnosis of Cervical Compressive Myelopathy. Issue 3 (1st February 2015)

• Record Type: Journal Article
• Authors: Funaba, Masahiro; Kanchiku, Tsukasa; Imajo, Yasuaki; Suzuki, Hidenori; Yoshida, Yuichiro; Nishida, Norihiro; Taguchi, Toshihiko
• Is Part Of: Spine. Volume 40:Issue 3(2015)
• Publication Date: 2015-02-01
• Subjects: Spine -- Abnormalities -- Periodicals; Spine -- Diseases -- Periodicals; Spine -- Surgery -- Periodicals; 616.73005
• DOI: 10.1097/BRS.0000000000000698
• Languages: English
• ISSNs: 0362-2436

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Study Design.</title> <p>Single-center retrospective study.</p> </sec> <sec> <title>Objective.</title> <p>To reveal the characteristic changes in central motor conduction time (CMCT) produced by transcranial magnetic stimulation among the responsible levels of cervical compressive myelopathy (CCM).</p> </sec> <sec> <title>Summary of Background Data.</title> <p>CMCT is a useful and noninvasive measure for evaluating the central motor pathway. However, a systematic correlation between CMCT findings and the responsible level of CCM has so far not been addressed in a large patient cohort.</p> </sec> <sec> <title>Method.</title> <p>We measured CMCT in 75 patients with CCM who were determined by intraoperative spinal cord evoked potentials to have a single site of conduction abnormality at the intervertebral level. Twenty-one healthy controls were also evaluated. Motor evoked potentials, compound muscle action potentials, and F wave were recorded from bilateral abductor digiti minimi (ADM) and abductor hallucis (AH) muscles. CMCT was calculated as follows: motor evoked potentials latency − (CMAPs latency + F latency − 1)/2 (ms).</p> </sec> <sec> <title>Result.</title> <p>The mean values of ADM-CMCT and AH-CMCT at each responsible level were significantly longer than those of normal values (<italic>P</italic> < 0.01). However, the mean value of ADM-CMCT at the C6–C7 level was markedly shorter than those at the other levels, whereas the mean values of AH-CMCT were not significantly different between each responsible level. We determined that an ADM-CMCT longer than 7.9 ms (mean + 2.5 standard deviation) was abnormal. Using this definition, the sensitivity of ADM-CMCT for CCM was 92% for C3–C4 myelopathy, 95% for C4–C5, 58% for C5–C6, and 9% for C6–C7.</p> </sec> <sec> <title>Conclusion.</title> <p>ADM-CMCT is useful for the screening of CCM rostral to the C5–C6 level. Diagnosis of patients with C6–C7 myelopathy should include assessment of the AH-CMCT.</p> <p> <bold>Level of Evidence:</bold> 4</p> </sec> </abstract>